1. Field of the Invention
This invention relates generally to diving equipment, and more particularly to an attitude adjusting device for scuba divers which utilizes free-moving weights to automatically vary the position of the ballast as the attitude of the diver changes to maintain a more efficient swimming position.
2. Brief Description of the Prior Art
In the following description the terms, as related to scuba diving, should be understood to have the following meanings. Buoyancy means the tendency to float or rise in the water. Ballast is meant to mean weights or heavy material carried by a diver to control stability and vertical distance in the water. Attitude is meant to mean the inclination of the diver's body relative to horizontal. Trim is meant to mean the adjustment of the diver's physical position while in the water by arranging the ballast. An ideal trim position would be perfectly horizontal.
Ballast devices and buoyancy compensator devices are known in the art. Buoyancy compensator devices or "BC's" are a relatively recent development and are vest-like devices worn on the torso of the diver and have a bladder which may be filled with air to control the buoyancy of the diver. In the event of an emergency, the ballast can be jettisoned and the B.C. quickly inflated to allow the diver to rise to the surface. Buoyancy compensator devices place the center of buoyancy above the diver's mid section.
Most buoyancy compensator devices have a cummerbund type belt having a quick release buckle which fastens in the front of the diver's waist. Most weight belts are also fastened by a quick release buckle in the front of the diver's waist. Often, the diver will have trouble quickly locating the proper buckle to release in an emergency and could accidentally release the wrong device.
Conventional weight belts are undesirable for many reasons. Unsecured weights can interfere with the operation of the quick release buckle. Weight belts are difficult to tighten snugly and can rotate on the wearer and, as the weight shifts, the diver will list to one side. Weight belts are also uncomfortable due to the pressure placed on the hips by the weights. In some cases, especially with women divers, bruises may appear in the hip area.
Buoyancy control and proper weighting are among the most important skills of scuba diving. A proper distribution of weight will allow the diver to maintain a perfectly horizontal, face-down position underwater while motionless. The incorrect amount of weight and wrong placement of the weight contribute to an undesirable, uncomfortable, and inefficient swimming attitude in the water. Overweighting forces a diver to have excessive air in his or her buoyancy compensator to achieve neutral buoyancy and raises the diver from the proper horizontal position. The more air required in the buoyancy compensator, the more difficult it is to control buoyancy during changes in depth and during descents and ascents. Because of the air in the lungs and the buoyancy compensator and the placement of the weight belt on the hip, divers tend to assume a somewhat head-up attitude in the water.
The head-up position increases the cross-sectional area, resulting in increased drag, which requires more energy for swimming. The more energy required, the more air consumed, and consequently less time beneath the surface.
Most weight devices including weight belts position the weight or ballast near the mid-section of the diver. This weight remains stationary throughout the dive period. In an attempt to achieve the ideal horizontal position or attitude, some divers will place a few pounds of weight near the top of their air tank. Although a diver will change attitudes many times during the diving period, the weights remain fixed for one attitude or position.
The most efficient trim adjustment would be to provide more weight in the head and shoulder area near the top of the air tank for a head-down attitude and to provide more weight in the mid-section area for a head-up attitude. Attitudes between these two extremes would require positioning of the weight along the longitudinal plane of the diver's body at certain locations to achieve the desired attitude.
There are several patents which disclose various weight systems and devices for controlling the buoyancy of a scuba diver.
Edmund, U.S. Pat. No. 2,968,159 discloses a combined air tank and weight carrier with a pair of parallel, laterally spaced tubes into which a plurality of short cylindrical metal weights are received in stacked relation. The short cylindrical weights allow the diver to more easily carry the total amount of weight necessary to overcome buoyancy. A pin at the bottom of the tubes allow the weights to be quickly dumped from the bottom of the tubes in an emergency so that the diver will rise immediately to the surface.
Crose, U.S. Pat. No. 3,379,023 discloses a pair of balance tanks which fit onto the divers air tank and are adapted to be filled and depleted of water by displacing it with air. The device controls buoyancy by adding or subtracting weight.
Denis, U.S. Pat. No. 3,967,459 discloses an independent weight system which is attached to a divers air tank. The system includes a pair of tubes which receive short cylindrical weights. A pin at the bottom of the tubes allow the weights to be quickly released. The weight carrying tubes are attached to the air tank such that the center of gravity of the underwater breathing equipment and attached weight system is below the overall center of buoyancy. By placing the center of gravity below the center of buoyancy, the diver will tend to assume a vertical head-up position, whereas the present invention utilizes the center of buoyancy as a fulcrum point for the movement of the weights in the weight tubes to assume a proper trim position relative to a horizontal axis.
Zambrano, U.S. Pat. No. 3,269,129 discloses a back pack for a diver's air tank including a pair of tubes which attach to the diver's air tank and into which a plurality of short cylindrical metal weights are received in stacked relation. A pin at the bottom of the tubes allows the weights to be quickly dumped from the bottom of the tubes in an emergency so that the diver will rise immediately to the surface. This device is an improvement over the Edmund device in that a compression spring disposed in the tubes above the weights keep them at their lowermost position and will forcefully eject the weights when the pin is pulled and vent holes above the weights facilitates jettisoning of the weights.
Although Zambrano was designed prior to the development of buoyancy compensator devices, he recognized the problem of maintaining a proper attitude in the water and suggests that the spring may be removed or pinned in the compressed condition allowing the weights to slide in the tubes from one end to the other as the diver tilts his body upward or downward. However, the solid weight cylinders sliding from one end to the other would not allow the ballast to be distributed in a manner to obtain a horizontal swimming position, and additional energy would be expended in attempting to overcome the upward or downward diving angle to maintain a horizontal swimming position.
Bartlett, U.S. Pat. No. 3,964,266 discloses a back pack for divers which is filled or depleted with air to achieve neutral buoyancy. A weight at the bottom of the pack is quickly released by a spring biased pin.
Shieh, U.S. Pat. No. 4,498,878 discloses a back pack for divers which merely carries a variety of life saving equipment.
The present invention is distinguished over the prior art in general, and these patents in particular by an attitude adjusting apparatus for use by scuba divers which automatically varies the position of ballast relative to the center of buoyancy as the attitude of their body underwater changes. An elongate hollow weight tube enclosed at one end has a removable closure at the opposite end and contains a quantity of small metal balls or shot. The weight tube is carried in close proximity to the torso of the diver in a position with its longitudinal axis generally parallel to the longitudinal axis of the torso of the diver. The free-moving balls or shot are movably disposed within the interior of the weight tube and are movably distributed at varying locations within the weight tube between a forward lowermost position as the diver assumes a descending head-down position and a rearward lowermost position as the diver assumes an ascending head-up position, and will be distributed along the length of the weight tube as the diver assumes a horizontal position. One or more weight tubes are releasably connected to a diver's air tank or back board by a quick release snap-fit coupling having a resilient jettisoning mechanism which allows the weight tubes to be quickly disconnected and forcefully propelled away from the diver in the event of an emergency. The weight tubes may also be releasably carried in pockets on a buoyancy compensator vest worn by the diver.